The present invention relates to a water-decomposable non-woven fabric which can be easily broken end dispersed by throwing into a large amount of water.
Non-woven fabrics have been widely used as a material for disposable absorbent articles such as sanitary napkins and paper diapers.
The non-woven fabrics used for the absorbent articles must have a toughness sufficient for resisting to breakage when they are wetted with a body fluid such as the menstrual blood or urine. Therefore, water-insoluble resins are generally used as a binder to bind fibers.
On the other hand, it is required of the non-woven fabrics to be used for the disposable absorbent articles or diaper liners that they can be untied into fine pieces and dispersed in water (water-decomposability) so that they can be thrown into a flush toilet. The above-described non-woven fabrics using water-insoluble resins as a binder are, therefore, unsatisfactory in view of these uses.
So far several proposals have been made on the water-decomposable non-woven fabric. For example, Japanese Patent Unexamined Published Application (hereinafter referred to as "J.P. KOKAI") No. Hei 1-306661 discloses a water-decomposable non-woven fabric comprising a water-decomposable fabric layer, each of faber of which is bound with one another using a water-soluble binder mainly containing an unsaturated carboxylic acid/unsaturated carboxylic acid ester copolymer in which a part of the unsaturated carboxylic acid is neutralized to form a salt. In this case, a fiber web is prepared from viscose rayon fibers having a length of 26 mm and a size of 2 denier by airlay method. However, since the viscose rayon fibers employed are or ordinal crimp numbers, i.e., not more than 19/inch, the resulting water-decomposable non-woven fabric has weak mechanical strength. The content of binder in the non-woven fabric was increased in order to increase the mechanical strength, but the resulting non-woven fabric became hard and sufficient mechanical strength could not be obtained, which properties were still unsatisfactory in the practical view points.